Spindle motor and recording disk driving device including the same

Abstract

There is provided a spindle motor including: a stator core fixedly installed on a stator; a driving magnet having a center thereof disposed to coincide with that of the stator core in an axial direction; and a rotor hub including a hub body having a disk shape, a magnet mounting part extended from an edge of the hub body in a downward axial direction and having the driving magnet installed on an inner peripheral surface thereof, and a disk supporting part extended from the magnet mounting part in a radial direction, wherein the stator includes a base member, and a pulling magnet is installed on at least one of a lower surface of the disk supporting part and an upper surface of the base member disposed to face the lower surface of the disk supporting part.

What is claimed is: 
     
         1 . A spindle motor comprising:
 a stator core fixedly installed on a stator;   a driving magnet having a center thereof disposed to coincide with that of the stator core in an axial direction; and   a rotor hub including a hub body having a disk shape, a magnet mounting part extended from an edge of the hub body in a downward axial direction and having the driving magnet installed on an inner peripheral surface thereof, and a disk supporting part extended from the magnet mounting part in a radial direction,   wherein the stator includes a base member, and   a pulling magnet is installed on at least one of a lower surface of the disk supporting part and an upper surface of the base member disposed to face the lower surface of the disk supporting part.   
     
     
         2 . The spindle motor of  claim 1 , wherein the driving magnet and the pulling magnet are formed of different materials. 
     
     
         3 . The spindle motor of  claim 2 , wherein the driving magnet and the pulling magnet are disposed to be spaced apart from each other by a predetermined distance in the radial direction. 
     
     
         4 . The spindle motor of  claim 2 , wherein the pulling magnet is formed of a rubber magnet containing Sr-Ferrite or Ba-Ferrite and having a residual magnetic flux density of 2 to 4 KGauss, and
 the driving magnet is formed of a rare-earth magnet having a residual magnetic flux density of 6 to 15 KGauss.   
     
     
         5 . The spindle motor of  claim 1 , wherein the pulling magnet is inserted into an installation groove recessed from the lower surface of the disk supporting part, and
 the stator further includes a pulling plate inserted into a mounting groove formed in the upper surface of the base member to generate pulling force in conjunction with the pulling magnet.   
     
     
         6 . The spindle motor of  claim 5 , wherein the base member is formed of a diamagnetic or non-magnetic material. 
     
     
         7 . The spindle motor of  claim 1 , wherein the pulling magnet is inserted into an installation groove recessed from the lower surface of the disk supporting part, and
 the base member is formed of a ferromagnetic material so as to generate pulling force in conjunction with the pulling magnet.   
     
     
         8 . The spindle motor of  claim 1 , wherein the pulling magnet is inserted into a mounting groove formed in the upper surface of the base member, and
 the rotor hub is formed of a ferromagnetic material so as to generate pulling force in conjunction with the pulling magnet.   
     
     
         9 . The spindle motor of  claim 1 , wherein the pulling magnet has a ring shape or a plurality of pulling magnets are disposed to be spaced apart from each other in a circumferential direction. 
     
     
         10 . The spindle motor of  claim 1 , wherein the base member includes an installation part having the stator core installed on an outer peripheral surface thereof. 
     
     
         11 . The spindle motor of  claim 10 , wherein the stator further includes a sleeve supporting a shaft rotating together with the rotor hub. 
     
     
         12 . The spindle motor of  claim 10 , wherein the stator further includes a lower thrust member fixedly installed on the installation part and a shaft having a lower end portion fixed to the lower thrust member, and
 the rotor hub is extended from a sleeve rotating around the shaft.   
     
     
         13 . A recording disk driving device comprising:
 the spindle motor of  claim 1  rotating a recording disk;   a head transfer part transferring a head detecting information of the recording disk mounted on the spindle motor to the recording disk; and   a housing accommodating the spindle motor and the head transfer part therein.